1. Technical Field
The present invention generally relates to a controlled reception pattern antenna, and more particularly, to a Global Navigation Satellite System (GNSS)-controlled reception pattern antenna for removing interference signals.
2. Description of the Related Art
The Global Navigation Satellite System (GNSS), represented by the Global Positioning System (GPS), is a satellite navigation system that precisely measures a user's position and provides visual information by receiving information about a satellite position, time, and error correction factors, from a satellite.
Currently, the GNSS is variously used in land, sea, and air systems in various military and civilian fields.
The GNSS is a communication system of which a reception structure for satellite signals has been disclosed, and has a weak reception signal because the satellite signal is transmitted from a long distance, more than about 20,000 km.
Therefore, the GNSS is very weakly resistant to unintentional electromagnetic interference such as multipath interference, or to intentional electromagnetic jamming.
In particular, if the GNSS system is jammed while providing accurate visual information to national infrastructures such as mobile communications, finances, Digital Multimedia Broadcasting (DMB), and smart grids, serious problems may result.
As a representative conventional art for responding to jamming or interference, which may be serious threats to the GNSS, there is a method that removes jamming signals using an array antenna. This is a technique whereby signals to a desired direction are increased and unwanted jamming signals are reduced by spatially disposing multiple antennas and applying a complex weighting to the respective outputs. Specifically, Korean Patent Application Publication No. 2011-0118385 discloses a method in which the gain in the direction of an antenna beam is controlled by adjusting the phase adjustment values of one or more phase controllers, connected to each antenna element.
However, such techniques consider only array antenna operating scenarios and digital signal processing methods, and do not provide a method for designing the array antenna itself.
Also, to install an array antenna in a mobile vehicle (automobiles, trains, vessels, aircrafts, etc.), it is critical to reduce the size of the array antenna. However, when the size of the array antenna decreases, the distance between elements of the antenna is decreased. As a result, mutual coupling increases, and distortion is generated in the antenna pattern by finite ground effects. Eventually, there would be a problem in that the antenna gain decreases at a low elevation angle.
Alternatively, as a related conventional art, U.S. Patent Publication No. 2014-0247194 discloses increasing an antenna bandwidth by disposing a plurality of low-loss Teflon substrates between a radiating element and a ground plane.
Also, as another related conventional art, a dual-bandwidth GPS patch antenna having a hybrid feeding structure was disclosed in the journal of the Korea Electromagnetic Engineering Society (Vol. 24, No. 7, pp. 678-685, “Design of a dual-band GPS array antenna”, July, 2013, Heeyoung Kim, et al.).